Download or read book Unsteady Flow Phenomena in Turbomachines written by Edward M. Greitzer and published by . This book was released on 1990 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes work carried out at the Gas Turbine Laboratory at M.I.T. as part of our multi-investigator effort on basic unsteady flow phenomena. Within the overall project, four separate tasks are specified. These are, in brief: I. Unsteady Flow in Compressors; II. Computational Techniques for Unsteady Flows; III. Unsteady Phenomena, Inlet Distortion, and Flow Instabilities in Multistage Compressors; IV. Unsteady Vortical Wakes Behind Blade Rows - Prediction of Relationships with Blade Properties. Computational fluid mechanics; Unsteady flows in turbomachines; Vortex wakes; Compressor stability; Transonic compressors. (jes).
Download or read book Unsteady Phenomena in Turbomachinery written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1976 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Flow Phenomena in Centrifugal Turbomachinery written by D. A. Fink and published by . This book was released on 1986 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research is an experimental investigation of system dynamics, unsteady effects, and detailed flow instabilities in a centrifugal compressor. The surge line, which marks the onset of instability and hence limits the minimum stable operating regime, is a primary design constraint in matching the compressor to downstream turbine and combustor (gas turbine gas generator) or diesel engine (turbocharger). the ultimate goal of this research is a thorough understanding of the events occurring in the compression system which cause surge.
Download or read book Unsteady Flow in Turbomachinery written by Ronald Mailach and published by . This book was released on 2010 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main source of unsteadiness in the stable operating range of turbomachinery is the aerodynamical interaction of the rotor and stator rows. The blades and vanes, moving relatively to each other, interact due to viscous wakes, secondary flow phenomena as well as potential effects. As a result of this, the real flow field is highly periodically unsteady and very complex, especially in multistage engines. These effects are not yet typically addressed in current design systems of turbomachinery. It is therefore a challenge to include beneficial unsteady and secondary flow effects to improve the engine performance. This requires a detailed physical understanding of the flow field as well as the resulting influences on performance and flow stability. The present work focuses on the effects appearing in multistage axial compressors. Different aspects of blade row interactions in a four-stage low-speed compressor are discussed in comparison to the existing physical understanding. This includes experimental results on the periodical unsteady flow field within the axial gaps between the blade rows as well as the flow field within the rotor blade passages. Furthermore, the unsteady behaviour of the blade boundary layer is considered. Other discussed aspects are the influence of wakes and potential effects on the unsteady profile pressures and the excited blade pressure forces. With this work a comprehensive picture on the different features of blade row interaction is drawn."--Back cover.
Download or read book Unsteady and Three Dimensional Flow in Turbomachines written by and published by . This book was released on 1999 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes work carried out at the Gas Turbine Laboratory at MIT during the period 3/1/96-9/30/99, as part of a multi-investigator effort on unsteady and three dimensional flow phenomena in turbomachines. Within the overall project, three separate tasks are specified. These are, in brief: (1) Characterization of Fully-Scaled, Unsteady Film-Cooled Turbine Blade Heat Transfer and Aerodynamics; (2) Flow Control in Compression Systems by Viscous Flow Removal; and (3) Unsteady Phenomena in Turbomachinery Endwall Flows.
Download or read book Unsteady Aerodynamics and Aeroelasticity of Turbomachines written by Yoshimichi Tanida and published by Elsevier Publishing Company. This book was released on 1995 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contributed papers in this volume cover a variety of unsteady flow phenomena in turbomachines. They present theoretical and numerical modellings plus experimental techniques and findings on the unsteady flows in turbomachines.
Download or read book Unsteady Phenomena in Turbomachinery written by ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT PARIS (France) and published by . This book was released on 1976 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: In designing the blading of a compressor or turbine the airflow is assumed to be steady. In reality the flow must always be unsteady. Small-scale disturbances arise from the proximity of passing blades; sometimes large scale disturbances result from distorted inlet flows. In a compressor, self-excited large scale disturbances may occur in the form of rotating stall. These unsteady effects are important because they may limit the range of efficient operation, or they may excite destructive blade vibrations. During recent years, improved instruments have enabled unsteady flows to be measured within cascades and turbomachines. The attention of the Meeting will be focussed on the improved understanding so obtained of the fluid mechanics of unsteady turbomachinery flows, the ways in which this understanding can be expressed in theoretical models, and the practical application of the research to turbomachinery design. (Author).
Download or read book Turbulence and Complex Flow Phenomena in Axial Turbomachines written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to measure the unsteady flow in axial turbomachines and use the data to address turbulence and complex flow modeling issues. The measurements are performed in an optically index matched facility, which allows unobstructed 2-D and Stereo PIV measurements within an entire stage. The data provide unprecedented insight on blade blade, blade-wake, wake-boundary layer and wake-wake interactions in the hub, mid-span and tip regions. Turbulence and unsteady flow phenomena are investigated at three levels: Passage-averaged steady RANS, unsteady RANS, and LES. Data analysis provides the distributions of deterministic Reynolds and sub-grid stresses, deterministic and turbulent kinetic energy, turbulence production and dissipation, as well as energy exchange between the average passage flow, the turbulence at different scales, and the deterministic energy.
Download or read book Turbulence and Complex Flow Phenomena in Multi stage Axial Turbomachines written by Joseph Katz and published by . This book was released on 2007 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to measure the flow within axial turbomachines and use the data to address turbulence modeling issues. Measurements are performed in two-stage transparent machines located in an optically index matched facility, which allows unobstructed 2-D and Stereo PIV measurements. Data provide insight on blade-wake, wake- boundary layer and wake-wake interactions. This report examines and elucidates several phenomena: i. Variations in turbulence within a wake generated by an upstream IGV blade while being ingested by a rotor passage; ii. Non-uniform turbulence production and diffusion leading to formation of turbulent hot spots within a rotor wake due to flow non-uniformities generated by upstream wakes; iii. Unsteady flow caused by an upstream wake stabilizes the boundary layer on a rotor blade and reduces its momentum thickness; iv. Comparisons of data covering an entire stage to RANS predictions; and V. Measurements of subgrid-scale stresses and dissipation rate, and comparisons to model predictions as well as associated implications of spatial averaging in followed by ensemble averaging in sustially non-uniform flows.
Download or read book Simulations of Unsteady Flow Phenomena in Cross flow Turbines written by Mukul Dave and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cross-flow turbines (CFT) harvest energy from wind or water currents via rotation about an axis perpendicular to the flow, and are a complementary technology to the more common axial-flow turbine. During the 360 degree rotation, the CFT blades experience a cyclical variation in the angle of attack and velocity relative to the oncoming flow, leading to flow separation and reattachment, otherwise known as dynamic stall. This causes an instantaneous loss in torque generation and unsteady force fluctuations which pose a challenge to accurate models and predictions of both the performance and the flow field. This work first examines the dynamic stall process and resulting wake features of CFTs under confined configurations applicable to river and tidal currents. High fidelity large-eddy simulations (LES) of a straight-bladed two-blade cross-flow turbine operating at a moderate Reynolds number are compared to unsteady Reynolds-averaged Navier-Stokes (RANS) simulations. The RANS model is shown to be sensitive to confinement at the simulated tip speed ratio as it over-predicts power generation due to suppression of flow separation. Results are compared with an unconfined configuration for which the RANS model successfully predicts a power curve, however displays significant differences in the evolution of flow structures. Next, the stall development is investigated via proper orthogonal decomposition (POD) of the velocity fields from LES. The POD modes' time development coefficients capture the trend of aerodynamic loads on the blade, along with critical events such as vortex formation and detachment. Flow curvature, history effects, and flow induction are identified as significant factors changing the blade aerodynamic loads as compared to pitching or plunging foils. Lastly, a previously optimized intracycle control of angular velocity that enhances power generation by 40% is compared to constant velocity control. This is enabled by a delay in the blade stall and an alignment of peak torque with the peak of blade angular velocity.
Download or read book AGARD Conference Proceedings written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development and published by . This book was released on 1978 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Phenomena in Turbomachinery written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Propulsion and Energetics Panel and published by . This book was released on 1976 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Flow in Turbomachines written by and published by . This book was released on 1984 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Aerodynamics and Aeroelasticity of Turbomachines written by Torsten H. Fransson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 835 pages. Available in PDF, EPUB and Kindle. Book excerpt: Twenty-one years have passed since the first symposium in this series was held in Paris (1976). Since then there have been meetings in Lausanne (1980), Cambridge (1984), Aachen (1987), Beijing (1989), Notre Dame (1991) and Fukuoka (1994). During this period a tremendous development in the field of unsteady aerodynamics and aeroelasticity in turbomachines has taken place. As steady-state flow conditions become better known, and as blades in the turbomachine are constantly pushed towards lower weight, and higher load and efficiency, the importance of unsteady phenomena appear more clearly. th The 8 Symposium was, as the previous ones, of high quality. Furthermore, it presented the audience with the latest developments in experimental, numerical and theoretical research. More papers than ever before were submitted to the conference. As the organising committee wanted to preserve the uniqueness of the symposium by having single sessions, and thus mingle speakers and audience with different backgrounds in this interdisciplinary field, only a limited number of papers could be accepted. 54 papers were accepted and presented at the meeting, all of which are included in the present proceedings.
Download or read book Unsteady Aerodynamics Aeroacoustics and Aeroelasticity of Turbomachines and Propellers written by H.M. Atassi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 876 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first International Symposium on Unsteady Aerodynamics and Aero elasticity of Turbomachines was held in Paris in 1976, and was followed by symposia at Lausanne in 1980, Cambridge in 1984, Aachen in 1987, Bei jing in 1989, and Notre Dame in 1991. The proceedings published following these symposia have become recognized both as basic reference texts in the subject area and as useful guides to progress in the field. It is hoped that this volume, which represents the proceedings of the Sixth International Symposium on Unsteady Aerodynamics of Turbomachines, will continue that tradition. Interest in the unsteady aerodynamics, aeroacoustics, and aeroelasticity of turbomachines has been growing rapidly since the Paris symposium. This expanded interest is reflected by a significant increase in the numbers of contributed papers and symposium participants. The timeliness of the topics has always been an essential objective of these symposia. Another important objective is to promote an international exchange between scien tists and engineers from universities, government agencies, and industry on the fascinating phenomena of unsteady turbomachine flows and how they affect the aeroelastic stability of the blading system and cause the radiation of unwanted noise. This exchange acts as a catalyst for the development of new analytical and numerical models along with carefully designed ex periments to help understand the behavior of such systems and to develop predictive tools for engineering applications.
Download or read book Unsteady Flow in Turbomachines written by and published by . This book was released on 1979 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Aerodynamic Phenomena in Turbomachines written by ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE) and published by . This book was released on 1990 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Specialists' Meeting was arranged in the following sessions: Flutter or Oscillating Cascades (5); Wakes or Complete Stage (10); Transonic and Supersonic Unsteady Phenomena (4); and Experimental Studies and Instrumentation Problems (5). The Technical Evaluation Report is included at the beginning of the Proceedings. Questions and answers of the discussions follow each paper. While around isolated airfoils many results on unsteady aerodynamic phenomena are available, reliable experimental data for unsteady turbomachinery flows were still missing. Therefore, the Specialists' Meeting offered a forum for experts to discuss the degree of advancements in this field. It was found that CFD with large numerical codes will be more and more developed and offer a useful tool for designers to improve their products. The experimental work for code validation is lagging somewhat behind. Keywords: Blades; Cascade; Compressors; Flutter; Oscillation; Supersonic flow; Transonic flow; Turbines; Unsteady aerodynamic; Vibration; Wakes; Symposia; Turbomachines. (jhd).
